VPP-44: iOAM service and path verification using shamir's secret sharing

Change-Id: I445ad13f8f93cb75cacc94192c4ae85c8ca14e35
Signed-off-by: Shwetha Bhandari <shwethab@cisco.com>

7 files changed, 1127 insertions, 12 deletions

diff --git a/vnet/Makefile.am b/vnet/Makefile.am
index 9393c1a8..1239a8b8 100644
--- a/vnet/Makefile.am
+++ b/vnet/Makefile.am
@@ -733,6 +733,16 @@ libvnetplugin_la_SOURCES +=                    \
 nobase_include_HEADERS +=                      \
   vnet/plugin/plugin.h
 
+########################################
+# Service Chain verification util
+########################################
+libvnet_la_SOURCES +=       \
+ vnet/lib-scv/scv_util.c
+
+nobase_include_HEADERS +=                       \
+ vnet/lib-scv/scv_util.h                        \
+ vnet/lib-scv/math64.h
+
 lib_LTLIBRARIES = libvnet.la libvnetplugin.la
 
 dpdk_libs = 
diff --git a/vnet/vnet/ip/ip6_hop_by_hop.c b/vnet/vnet/ip/ip6_hop_by_hop.c
index 2282e8ca..16650dde 100644
--- a/vnet/vnet/ip/ip6_hop_by_hop.c
+++ b/vnet/vnet/ip/ip6_hop_by_hop.c
@@ -24,6 +24,7 @@
 #include <vppinfra/elog.h>
 
 #include <vnet/ip/ip6_hop_by_hop.h>
+#include <vnet/lib-scv/scv_util.h>
 
 /* Timestamp precision multipliers for seconds, milliseconds, microseconds
  * and nanoseconds respectively.
@@ -157,6 +158,21 @@ static u8 * format_ioam_data_list_element (u8 * s, va_list * args)
  
   return s;
 }
+static u8 * format_ioam_pow (u8 * s, va_list * args)
+{
+  ioam_pow_option_t * pow0 = va_arg (*args, ioam_pow_option_t *);
+  u64 random, cumulative;
+  random = cumulative = 0;
+  if (pow0) 
+    { 
+      random = clib_net_to_host_u64 (pow0->random);
+      cumulative = clib_net_to_host_u64 (pow0->cumulative);
+    }
+
+  s = format (s, "random = 0x%Lx, Cumulative = 0x%Lx, Index = 0x%x", 
+	      random, cumulative, pow0->reserved_profile_id);
+  return s;
+}
 
 static u8 * format_ip6_hop_by_hop_trace (u8 * s, va_list * args)
 {
@@ -170,6 +186,7 @@ static u8 * format_ip6_hop_by_hop_trace (u8 * s, va_list * args)
   u32 * elt0;
   int elt_index;
   u8 type0;
+  ioam_pow_option_t * pow0;
   
   hbh0 = (ip6_hop_by_hop_header_t *)t->option_data;
 
@@ -211,6 +228,9 @@ static u8 * format_ip6_hop_by_hop_trace (u8 * s, va_list * args)
 
         case HBH_OPTION_TYPE_IOAM_PROOF_OF_WORK:
           s = format (s, "    POW opt present\n");
+	  pow0 = (ioam_pow_option_t *) opt0;     
+          s = format (s, "         %U\n", format_ioam_pow,pow0);      
+ 
           opt0 = (ip6_hop_by_hop_option_t *) 
             (((u8 *)opt0) + sizeof (ioam_pow_option_t));
           break;
@@ -234,6 +254,7 @@ vlib_node_registration_t ip6_hop_by_hop_node;
 
 #define foreach_ip6_hop_by_hop_error \
 _(PROCESSED, "Pkts with ip6 hop-by-hop options") \
+_(PROFILE_MISS, "Pkts with ip6 hop-by-hop options but no profile set") \
 _(UNKNOWN_OPTION, "Unknown ip6 hop-by-hop options")
 
 typedef enum {
@@ -359,9 +380,12 @@ ip6_hop_by_hop_node_fn (vlib_main_t * vm,
           ip6_hop_by_hop_header_t *hbh0;
           ip6_hop_by_hop_option_t *opt0, *limit0;
           ioam_trace_option_t * trace0;
+	  ioam_pow_option_t * pow0;
           u32 * elt0;
           u8 type0;
-         
+          u64 random = 0, cumulative = 0;
+	  u8 pow_encap = 0;
+	  
           /* speculatively enqueue b0 to the current next frame */
 	  bi0 = from[0];
 	  to_next[0] = bi0;
@@ -439,6 +463,96 @@ ip6_hop_by_hop_node_fn (vlib_main_t * vm,
                   break;
 
                 case HBH_OPTION_TYPE_IOAM_PROOF_OF_WORK:
+		  pow_profile = scv_profile_find(pow_profile_index);
+		  if (PREDICT_FALSE(!pow_profile))
+		    {
+		      vlib_node_increment_counter (vm, 
+						   ip6_hop_by_hop_node.index,
+						   IP6_HOP_BY_HOP_ERROR_PROFILE_MISS, 1);
+
+		      opt0 = (ip6_hop_by_hop_option_t *) 
+			(((u8 *)opt0) + sizeof (ioam_pow_option_t));
+		      break;
+		    }
+		  pow0 = (ioam_pow_option_t *) opt0;
+		  pow_encap = (pow0->random == 0);
+                  if (pow_encap)
+                    {
+                      if (PREDICT_FALSE(total_pkts_using_this_profile >= 
+					pow_profile->validity)) 
+                        {
+                          /* Choose a new profile */
+                          u16 new_profile_index;
+                          new_profile_index = 
+                            scv_get_next_profile_id(vm, 
+						    pow_profile_index);
+                          if (new_profile_index != pow_profile_index) 
+                            {   
+                              /* Got a new profile */
+                              scv_profile_invalidate(vm, hm,
+						     pow_profile_index, 
+						     pow_encap);
+                              pow_profile_index = new_profile_index;
+                              pow_profile =
+                                scv_profile_find(pow_profile_index);
+                              total_pkts_using_this_profile = 0;
+                            } 
+                          else 
+                            {
+                              scv_profile_invalidate(vm, hm,
+                                        pow_profile_index, 
+                                        pow_encap);
+			    }
+                        }
+                      pow0->reserved_profile_id =
+			pow_profile_index & PROFILE_ID_MASK;
+                      total_pkts_using_this_profile++;
+		    } 
+                  else 
+                    { /* Non encap node */
+                      if (PREDICT_FALSE(pow0->reserved_profile_id != 
+				      pow_profile_index)) 
+                        {
+                          /* New profile announced by encap node. */
+                          scv_profile *new_profile = 0;
+                          new_profile =
+			         scv_profile_find(pow0->reserved_profile_id); 
+                          if (PREDICT_FALSE(new_profile == 0 ||
+					  new_profile->validity == 0)) 
+                            {
+                              /* Profile is invalid. Use old profile*/
+                              vlib_node_increment_counter (vm, 
+						       ip6_hop_by_hop_node.index,
+						       IP6_HOP_BY_HOP_ERROR_PROFILE_MISS, 1);
+                              scv_profile_invalidate(vm, hm,
+						 pow0->reserved_profile_id, 
+						 pow_encap);
+                            } 
+                          else 
+                            {
+                              scv_profile_invalidate(vm, hm,
+						 pow_profile_index,
+						 pow_encap);
+                              pow_profile_index = pow0->reserved_profile_id;
+                              pow_profile = new_profile;
+                              total_pkts_using_this_profile = 0;
+			    }
+                        }
+                      total_pkts_using_this_profile++;
+                    }
+
+                  if (pow0->random == 0) 
+                    {
+                      pow0->random = clib_host_to_net_u64(
+					  scv_generate_random(pow_profile));
+                      pow0->cumulative = 0;
+                    }
+                  random = clib_net_to_host_u64(pow0->random);
+                  cumulative = clib_net_to_host_u64(pow0->cumulative);
+                  pow0->cumulative = clib_host_to_net_u64(
+							  scv_update_cumulative(pow_profile,
+										     cumulative,
+										     random));
                   opt0 = (ip6_hop_by_hop_option_t *) 
                     (((u8 *)opt0) + sizeof (ioam_pow_option_t));
                   break;
@@ -757,7 +871,9 @@ vlib_node_registration_t ip6_pop_hop_by_hop_node;
 
 #define foreach_ip6_pop_hop_by_hop_error                \
 _(PROCESSED, "Pkts w/ removed ip6 hop-by-hop options")  \
-_(NO_HOHO, "Pkts w/ no ip6 hop-by-hop options")
+_(NO_HOHO, "Pkts w/ no ip6 hop-by-hop options") \
+_(SCV_PASSED, "Pkts with SCV in Policy") \
+_(SCV_FAILED, "Pkts with SCV out of Policy") 
 
 typedef enum {
 #define _(sym,str) IP6_POP_HOP_BY_HOP_ERROR_##sym,
@@ -772,6 +888,69 @@ static char * ip6_pop_hop_by_hop_error_strings[] = {
 #undef _
 };
 
+static inline void ioam_end_of_path_validation (vlib_main_t * vm,
+                                                ip6_header_t *ip0,
+                                                ip6_hop_by_hop_header_t *hbh0)
+{
+  ip6_hop_by_hop_option_t *opt0, *limit0;
+  ioam_pow_option_t * pow0;
+  u8 type0;
+  u64 final_cumulative = 0;
+  u64 random = 0;
+  u8 result = 0;
+
+  if (!hbh0 || !ip0) return;
+
+  opt0 = (ip6_hop_by_hop_option_t *)(hbh0+1);
+  limit0 = (ip6_hop_by_hop_option_t *)
+    ((u8 *)hbh0 + ((hbh0->length+1)<<3));
+
+  /* Scan the set of h-b-h options, process ones that we understand */
+  while (opt0 < limit0)
+    {
+      type0 = opt0->type & HBH_OPTION_TYPE_MASK;
+      switch (type0)
+        {
+        case HBH_OPTION_TYPE_IOAM_EDGE_TO_EDGE:
+        case HBH_OPTION_TYPE_IOAM_TRACE_DATA_LIST:
+          opt0 = (ip6_hop_by_hop_option_t *)
+            (((u8 *)opt0) + opt0->length
+             + sizeof (ip6_hop_by_hop_option_t));
+          break;
+        case HBH_OPTION_TYPE_IOAM_PROOF_OF_WORK:
+          pow0 = (ioam_pow_option_t *) opt0;
+          random = clib_net_to_host_u64(pow0->random);
+          final_cumulative = clib_net_to_host_u64(pow0->cumulative);
+          result =  scv_validate (pow_profile,
+                                       final_cumulative, random);
+	  
+          if (result == 1) 
+            {
+              vlib_node_increment_counter (vm, ip6_pop_hop_by_hop_node.index,
+					 IP6_POP_HOP_BY_HOP_ERROR_SCV_PASSED, result);
+            }
+          else 
+            {
+	      vlib_node_increment_counter (vm, ip6_pop_hop_by_hop_node.index,
+					 IP6_POP_HOP_BY_HOP_ERROR_SCV_FAILED, 1);
+            }
+	  /* TODO: notify the scv failure*/
+          opt0 = (ip6_hop_by_hop_option_t *)
+            (((u8 *)opt0) + sizeof (ioam_pow_option_t));
+          break;
+
+        case 0: /* Pad */
+          opt0 = (ip6_hop_by_hop_option_t *) ((u8 *)opt0) + 1;
+          break;
+
+        default:
+           format(0, "Something is wrong\n"); 
+           break;
+        }
+    }
+}
+
+
 static uword
 ip6_pop_hop_by_hop_node_fn (vlib_main_t * vm,
 		  vlib_node_runtime_t * node,
@@ -910,14 +1089,14 @@ ip6_pop_hop_by_hop_node_fn (vlib_main_t * vm,
                   next0 = IP6_HBYH_INPUT_NEXT_IP6_LOOKUP;
                   goto out1;
                 }
-              else
-                { /* Second pass */
-                  /* Collect data from trace via callback */
-                  next0 = ioam_end_of_path_cb ? 
-                          ioam_end_of_path_cb (vm, node, b0, ip0, adj0) :
-                          IP6_HBYH_INPUT_NEXT_IP6_REWRITE;
-                }
               
+              /* Second pass */
+              /* Collect data from trace via callback */
+              next0 = ioam_end_of_path_cb ? 
+                          ioam_end_of_path_cb (vm, node, b0, ip0, adj0) :
+		 IP6_HBYH_INPUT_NEXT_IP6_REWRITE;
+              /* TODO:Temporarily doing it here.. do this validation in end_of_path_cb */
+              ioam_end_of_path_validation(vm, ip0, hbh0);
               /* Pop the trace data */
               vlib_buffer_advance (b0, (hbh0->length+1)<<3);
               new_l0 = clib_net_to_host_u16 (ip0->payload_length) -
@@ -1377,11 +1556,13 @@ VLIB_CLI_COMMAND (ip6_set_ioam_destination_cmd, static) = {
   .function = ip6_set_ioam_destination_command_fn,
 };
 
+
 void vnet_register_ioam_end_of_path_callback (void *cb)
 {
   ip6_hop_by_hop_main_t * hm = &ip6_hop_by_hop_main;
 
   hm->ioam_end_of_path_cb = cb;
 }
+
                                              
 
diff --git a/vnet/vnet/ip/ip6_hop_by_hop.h b/vnet/vnet/ip/ip6_hop_by_hop.h
index 2ec83f2b..f9bec13e 100644
--- a/vnet/vnet/ip/ip6_hop_by_hop.h
+++ b/vnet/vnet/ip/ip6_hop_by_hop.h
@@ -16,6 +16,7 @@
 #define __included_ip6_hop_by_hop_h__
 
 #include <vnet/ip/ip6_hop_by_hop_packet.h>
+#include <vnet/ip/ip.h>
 
 typedef struct {
   /* The current rewrite we're using */
diff --git a/vnet/vnet/ip/ip6_hop_by_hop_packet.h b/vnet/vnet/ip/ip6_hop_by_hop_packet.h
index 22ca2055..57433acb 100644
--- a/vnet/vnet/ip/ip6_hop_by_hop_packet.h
+++ b/vnet/vnet/ip/ip6_hop_by_hop_packet.h
@@ -39,9 +39,9 @@ typedef struct {
 } ip6_hop_by_hop_option_t;
 
 /* $$$$ IANA banana constants */
-#define HBH_OPTION_TYPE_IOAM_TRACE_DATA_LIST 1
-#define HBH_OPTION_TYPE_IOAM_PROOF_OF_WORK 2
-#define HBH_OPTION_TYPE_IOAM_EDGE_TO_EDGE 3
+#define HBH_OPTION_TYPE_IOAM_TRACE_DATA_LIST 27
+#define HBH_OPTION_TYPE_IOAM_PROOF_OF_WORK 28
+#define HBH_OPTION_TYPE_IOAM_EDGE_TO_EDGE 29
 
 /*
 typedef struct {
diff --git a/vnet/vnet/lib-scv/math64.h b/vnet/vnet/lib-scv/math64.h
new file mode 100644
index 00000000..9ee6e438
--- /dev/null
+++ b/vnet/vnet/lib-scv/math64.h
@@ -0,0 +1,159 @@
+/* 
+ * math64.h provides the 64 bit unsigned integer add, multiply followed by  modulo operation
+ * The linux/math64.h provides divide and multiply 64 bit integers but:
+ * 1. multiply: mul_u64_u64_shr - only returns 64 bits of the result and has to be called
+ *                     twice to get the complete 128 bits of the result.
+ * 2. Modulo operation of the result of  addition and multiplication of u64 that may result 
+ *                        in integers > 64 bits is not supported
+ * Hence this header to combine add/multiply followed by modulo of u64 integrers
+ * always resulting in u64.
+ * 
+ * Copyright (c) 2015 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef include_vnet_math64_h
+#define include_vnet_math64_h
+#include <stdint.h>
+
+/* 
+ * multiplies and returns result in hi and lo 
+ */
+static inline void mul64by64(u64 a, u64 b, u64 * hi, u64 * lo)
+{
+    u64 a_lo = (u64) (uint32_t) a;
+    u64 a_hi = a >> 32;
+    u64 b_lo = (u64) (u32) b;
+    u64 b_hi = b >> 32;
+
+    u64 p0 = a_lo * b_lo;
+    u64 p1 = a_lo * b_hi;
+    u64 p2 = a_hi * b_lo;
+    u64 p3 = a_hi * b_hi;
+
+    u32 cy = (u32) (((p0 >> 32) + (u32) p1 + (u32) p2) >> 32);
+
+    *lo = p0 + (p1 << 32) + (p2 << 32);
+    *hi = p3 + (p1 >> 32) + (p2 >> 32) + cy;
+    return;
+}
+
+#define TWO64 18446744073709551616.0
+
+static inline u64 mod128by64(u64 x, u64 y, u64 m, double di)
+{
+    u64 q1, q2, q;
+    u64 p1, p0;
+    double dq;
+
+    /* calculate quotient first pass 53 bits */
+    dq = (TWO64 * (double)x + (double)y) * di;
+
+    if (dq >= TWO64)
+        q1 = 0xfffffffffffff800L;
+    else
+        q1 = dq;
+
+    /* q1 * m to compare the product to the dividend.  */
+    mul64by64(q1, m, &p1, &p0);
+
+    /* Adjust quotient. is it > actual result: */
+    if (x < p1 || (x == p1 && y < p0))
+    {
+        /* q1 > quotient.  calculate abs remainder */
+        x = p1 - (x + (p0 < y));
+        y = p0 - y;
+
+        /* use the remainder as new dividend to adjust quotient */
+        q2 = (u64) ((TWO64 * (double)x + (double)y) * di);
+        mul64by64(q2, m, &p1, &p0);
+
+        q = q1 - q2;
+        if (x < p1 || (x == p1 && y <= p0))
+        {
+            y = p0 - y;
+        }
+        else
+        {
+            y = p0 - y;
+            y += m;
+            q--;
+        }
+    }
+    else
+    {
+        x = x - (p1 + (y < p0));
+        y = y - p0;
+
+        q2 = (u64) ((TWO64 * (double)x + (double)y) * di);
+        mul64by64(q2, m, &p1, &p0);
+
+        q = q1 + q2;
+        if (x < p1 || (x == p1 && y < p0))
+        {
+            y = y - p0;
+            y += m;
+            q--;
+        }
+        else
+        {
+            y = y - p0;
+            if (y >= m)
+            {
+                y -= m;
+                q++;
+            }
+        }
+    }
+
+    return y;
+}
+
+/* 
+ * returns a % p
+ */
+static inline u64 mod64by64(u64 a, u64 p, u64 primeinv)
+{
+    return (mod128by64(0, a, p, primeinv));
+}
+
+static inline void add64(u64 a, u64 b, u64 * whi, u64 * wlo)
+{
+    *wlo = a + b;
+    if (*wlo < a)
+        *whi = 1;
+
+}
+
+/* 
+ * returns (a + b)%p
+ */
+static inline u64 add64_mod(u64 a, u64 b, u64 p, double pi)
+{
+    u64 shi = 0, slo = 0;
+
+    add64(a, b, &shi, &slo);
+    return (mod128by64(shi, slo, p, pi));
+}
+
+/* 
+ * returns (ab) % p
+ */
+static inline u64 mul64_mod(u64 a, u64 b, u64 p, double pi)
+{
+    u64 phi = 0, plo = 0;
+
+    mul64by64(a, b, &phi, &plo);
+    return (mod128by64(phi, plo, p, pi));
+}
+
+#endif
diff --git a/vnet/vnet/lib-scv/scv_util.c b/vnet/vnet/lib-scv/scv_util.c
new file mode 100644
index 00000000..e69c8837
--- /dev/null
+++ b/vnet/vnet/lib-scv/scv_util.c
@@ -0,0 +1,486 @@
+/* 
+ * Copyright (c) 2015 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <vnet/vnet.h>
+#include <stdint.h>
+#include <time.h>
+#include <string.h>
+#include <vppinfra/mem.h>
+#include "math64.h"
+#include "scv_util.h"
+
+scv_profile *pow_profile = NULL;
+u16 pow_profile_index = 0;
+u64 total_pkts_using_this_profile = 0;
+u8 chain_path_name[PATH_NAME_SIZE];
+scv_profile profile_list[MAX_SERVICE_PROFILES];
+u8 max_profiles = 0;
+u16 invalid_profile_start_index = 0;
+u8 number_of_invalid_profiles = 0;
+f64 next_time_to_send = 0;
+u32 time_exponent = 1;
+vlib_main_t *gvm = 0;
+
+static void scv_profile_init(scv_profile * new, u16 id)
+{
+    if (new)
+    {
+        memset(new, 0, sizeof(scv_profile));
+        new->id = id;
+    }
+}
+
+/* 
+ * Get maximum number of profiles configured for this chain.
+ */
+u8 scv_get_max_profiles(void)
+{
+    return max_profiles;
+}
+
+scv_profile *scv_profile_find(u16 id)
+{
+    u8 max = scv_get_max_profiles();
+
+    if (id >= 0 && id < max)
+    {
+        return (&profile_list[id]);
+    }
+    return (NULL);
+}
+
+u8 sc_init_done = 0;
+void scv_init(u8 * path_name, u8 max, u8 indx)
+{
+    int i = 0;
+
+    if (sc_init_done)
+    {
+        return;
+    }
+    memcpy(chain_path_name, path_name, strlen((const char *)path_name) + 1);
+    max_profiles = max;
+    pow_profile_index = indx;
+
+    for (i = 0; i < max_profiles; i++)
+    {
+        scv_profile_init(&profile_list[i], i);
+    }
+
+    sc_init_done = 1;
+}
+
+void scv_profile_cleanup(scv_profile * profile)
+{
+    u16 id = profile->id;
+
+    memset(profile, 0, sizeof(scv_profile));
+    profile->id = id;           /* Restore id alone */
+}
+
+void scv_profile_create(scv_profile * profile, u64 prime,
+    u64 poly2, u64 lpc, u64 secret_share, u64 validity)
+{
+    if (profile)
+    {
+        scv_profile_cleanup(profile);
+        profile->prime = prime;
+        profile->primeinv = 1.0 / prime;
+        profile->lpc = lpc;
+        profile->poly_pre_eval = poly2;
+        profile->secret_share = secret_share;
+        profile->validity = validity;
+        time_exponent = 1;      /* Got a new profile. Reset backoff */
+        next_time_to_send = 0;  /* and send next request with no delay */
+    }
+}
+
+void scv_set_validator(scv_profile * profile, u64 key)
+{
+    if (profile)
+    {
+        profile->validator = 1;
+        profile->secret_key = key;
+    }
+}
+
+static inline u64 sc_update_cumulative(u64 cumulative, u64 random,
+    u64 secret_share, u64 prime, u64 lpc, u64 pre_split, double prime_inv)
+{
+    u64 share_random = 0;
+    u64 cumulative_new = 0;
+
+    /* 
+     * calculate split share for random
+     */
+    share_random = add64_mod(pre_split, random, prime, prime_inv);
+
+    /* 
+     * lpc * (share_secret + share_random)
+     */
+    share_random = add64_mod(share_random, secret_share, prime, prime_inv);
+    share_random = mul64_mod(share_random, lpc, prime, prime_inv);
+
+    cumulative_new = add64_mod(cumulative, share_random, prime, prime_inv);
+
+    return (cumulative_new);
+}
+
+u64 scv_update_cumulative(scv_profile * profile, u64 cumulative, u64 random)
+{
+    if (profile && profile->validity != 0)
+    {
+        return (sc_update_cumulative(cumulative, random, profile->secret_share,
+                profile->prime, profile->lpc, profile->poly_pre_eval,
+                profile->primeinv));
+    }
+    return (0);
+}
+
+static u8 sc_validate(u64 secret, u64 prime, double prime_inv,
+    u64 cumulative, u64 random)
+{
+    if (cumulative == (random + secret))
+    {
+        return (1);
+    }
+    else if (cumulative == add64_mod(random, secret, prime, prime_inv))
+    {
+        return (1);
+    }
+    return (0);
+}
+
+/* 
+ * return True if the cumulative matches secret from a profile
+ */
+u8 scv_validate(scv_profile * profile, u64 cumulative, u64 random)
+{
+    if (profile && profile->validator)
+    {
+        return (sc_validate(profile->secret_key, profile->prime,
+                profile->primeinv, cumulative, random));
+    }
+    return (0);
+}
+
+/* 
+ * Utility function to get random number per pack
+ */
+u64 scv_generate_random(scv_profile * profile)
+{
+    u64 random = 0;
+    int32_t second_half;
+    static u32 seed = 0;
+
+    if (PREDICT_FALSE(!seed))
+        seed = random_default_seed();
+
+    /* 
+     * Upper 4 bytes seconds
+     */
+    random = (u64) time(NULL);
+
+    random &= 0xffffffff;
+    random = random << 32;
+    /* 
+     * Lower 4 bytes random number
+     */
+    second_half = random_u32(&seed);
+
+    random |= second_half;
+
+    if (PREDICT_TRUE(profile != NULL))
+    {
+        random &= profile->bit_mask;
+    }
+    return (random);
+}
+
+void scv_profile_set_bit_mask(scv_profile * profile, u16 bits)
+{
+    int sizeInBits;
+
+    if (profile)
+    {
+        sizeInBits = sizeof(profile->bit_mask) * 8;
+        profile->bit_mask =
+            (bits >=
+            sizeInBits ? (u64) - 1 : (u64) ((u64) 1 << (u64) bits) - 1);
+    }
+}
+
+/* 
+ * TODO: Use vector buffers and hash tables
+ */
+#define MAX_SERVICES 16
+
+clib_error_t *clear_scv_profile_command_fn(vlib_main_t * vm,
+    unformat_input_t * input, vlib_cli_command_t * cmd)
+{
+    int i = 0;
+
+    if (!sc_init_done)
+        return 0;
+
+    for (i = 0; i < max_profiles; i++)
+    {
+        scv_profile_cleanup(&profile_list[i]);
+    }
+    pow_profile = NULL;
+    pow_profile_index = 0;
+    total_pkts_using_this_profile = 0;
+    memset(chain_path_name, 0, PATH_NAME_SIZE);
+    max_profiles = 0;
+    invalid_profile_start_index = 0;
+    number_of_invalid_profiles = 0;
+    next_time_to_send = 0;
+    time_exponent = 1;
+    sc_init_done = 0;
+
+    return 0;
+}
+
+void clear_scv_profiles()
+{
+    clear_scv_profile_command_fn(0, 0, 0);
+}
+
+VLIB_CLI_COMMAND(clear_scv_profile_command) =
+{
+.path = "clear scv profile",
+.short_help = "clear scv profile [<index>|all]",
+.function = clear_scv_profile_command_fn,
+};
+
+static clib_error_t *set_scv_profile_command_fn(vlib_main_t * vm,
+    unformat_input_t * input, vlib_cli_command_t * cmd)
+{
+    u64 prime;
+    u64 secret_share, validity;
+    u64 secret_key;
+    u8 validator = 0;
+    u16 profile_id;
+    u32 bits;
+    u64 lpc = 0, poly2 = 0;
+    scv_profile *profile = NULL;
+
+    bits = MAX_BITS;
+
+    while (unformat_check_input(input) != UNFORMAT_END_OF_INPUT)
+    {
+        if (unformat(input, "id %d", &profile_id))
+            ;
+        else if (unformat(input, "validate-key 0x%Lx", &secret_key))
+            validator = 1;
+        else if (unformat(input, "prime-number 0x%Lx", &prime))
+            ;
+        else if (unformat(input, "secret_share 0x%Lx", &secret_share))
+            ;
+        else if (unformat(input, "polynomial2 0x%Lx", &poly2))
+            ;
+        else if (unformat(input, "lpc 0x%Lx", &lpc))
+            ;
+        else if (unformat(input, "validity 0x%Lx", &validity))
+            ;
+        else if (unformat(input, "bits-in-random %d", &bits))
+        {
+            if (bits > MAX_BITS)
+                bits = MAX_BITS;
+        }
+        else
+            return clib_error_return(0, "unknown input `%U'",
+                format_unformat_error, input);
+    }
+
+    scv_init((u8 *) "TEST", MAX_SERVICE_PROFILES, 0 /* start index */ );
+    profile = scv_profile_find(profile_id);
+
+    if (profile)
+    {
+        scv_profile_create(profile, prime, poly2, lpc, secret_share, validity);
+        if (validator)
+            scv_set_validator(profile, secret_key);
+        scv_profile_set_bit_mask(profile, bits);
+    }
+
+    return 0;
+}
+
+VLIB_CLI_COMMAND(set_scv_profile_command) =
+{
+.path = "set scv profile",
+.short_help = "set scv profile id [0-16] [validator-key 0xu64] \
+                  prime-number 0xu64 secret_share 0xu64 lpc 0xu64 \
+                  polynomial2 0xu64 bits-in-random [0-64] ",
+.function = set_scv_profile_command_fn,
+};
+
+static clib_error_t *show_scv_profile_command_fn(vlib_main_t * vm,
+    unformat_input_t * input, vlib_cli_command_t * cmd)
+{
+    scv_profile *p = NULL;
+    u16 i;
+    u8 *s = 0;
+
+    if (sc_init_done == 0)
+    {
+        s = format(s, "SCV Profiles not configured\n");
+        vlib_cli_output(vm, "%v", s);
+        return 0;
+    }
+
+    for (i = 0; i < max_profiles; i++)
+    {
+        p = scv_profile_find(i);
+        if (p->validity == 0)
+            continue;
+        s = format(s, "SCV Profile at index: %d\n", i);
+        s = format(s, "                 Id : %d\n", p->id);
+        s = format(s, "          Validator : %s (%d)\n",
+            (p->validator) ? "True" : "False", p->validator);
+        if (p->validator == 1)
+            s = format(s, "         Secret key : 0x%Lx (%Ld)\n",
+                p->secret_key, p->secret_key);
+        s = format(s, "       Secret share : 0x%Lx (%Ld)\n",
+            p->secret_share, p->secret_share);
+        s = format(s, "       Prime number : 0x%Lx (%Ld)\n",
+            p->prime, p->prime);
+        s = format(s, "2nd polynomial(eval) : 0x%Lx (%Ld)\n",
+            p->poly_pre_eval, p->poly_pre_eval);
+        s = format(s, "                 LPC : 0x%Lx (%Ld)\n", p->lpc, p->lpc);
+
+        s = format(s, "           Bit mask : 0x%Lx (%Ld)\n",
+            p->bit_mask, p->bit_mask);
+        s = format(s, "           Validity : 0x%Lx (%Ld)\n",
+            p->validity, p->validity);
+    }
+
+    if (max_profiles)
+    {
+        p = scv_profile_find(pow_profile_index);
+
+        s = format(s, "\nInvalid profiles start : %d Number : %d\n",
+            invalid_profile_start_index, number_of_invalid_profiles);
+
+        if (next_time_to_send)
+            s = format(s, "\nNext time to send : %U, time_exponent:%ld\n",
+                format_time_interval, "d:h:m:s:f:u",
+                next_time_to_send, time_exponent);
+        else
+            s = format(s, "\nNext time to send : Immediate\n");
+        s = format(s, "\nPath name : %s\n", chain_path_name);
+        s = format(s, "\nProfile index in use: %d\n", pow_profile_index);
+        s = format(s, "Pkts passed : 0x%Lx (validity:0x%Lx)\n",
+            total_pkts_using_this_profile, p->validity);
+        if (scv_is_decap(p))
+            s = format(s, "  This is Decap node.  \n");
+        vlib_cli_output(vm, "%v", s);
+    }
+    vec_free(s);
+
+    return 0;
+}
+
+VLIB_CLI_COMMAND(show_scv_profile_command) =
+{
+.path = "show scv profile",
+.short_help = "show scv profile",
+.function = show_scv_profile_command_fn,
+};
+
+static clib_error_t *test_profile_renew_refresh_fn(vlib_main_t * vm,
+    unformat_input_t * input, vlib_cli_command_t * cmd)
+{
+    u8 renew_or_refresh = 0;
+
+#define TEST_PROFILE_RENEW 1
+#define TEST_PROFILE_REFRESH 2
+    u8 *path_name = 0;
+    u32 start_index = 0, num_profiles = 0;
+    int rc = 0;
+
+    while (unformat_check_input(input) != UNFORMAT_END_OF_INPUT)
+    {
+        if (unformat(input, "path-name %s start-index %d num-profiles %d",
+                &path_name, &start_index, &num_profiles))
+            ;
+        else if (unformat(input, "renew"))
+            renew_or_refresh = TEST_PROFILE_RENEW;
+        else if (unformat(input, "refresh"))
+            renew_or_refresh = TEST_PROFILE_REFRESH;
+        else
+            break;
+    }
+
+    if (renew_or_refresh == TEST_PROFILE_RENEW)
+    {
+	
+        rc = scv_profile_renew(path_name, (u8) start_index, (u8) num_profiles);
+    }
+    else if (renew_or_refresh == TEST_PROFILE_REFRESH)
+    {
+	
+        rc = scv_profile_refresh(path_name, (u8) start_index,
+            (u8) num_profiles);
+    }
+    else
+    {
+        vec_free(path_name);
+        return clib_error_return(0, "Enter renew or refresh");
+    }
+
+    vlib_cli_output(vm, "%s notification %s. rc = %d\n",
+        (renew_or_refresh == TEST_PROFILE_RENEW) ? "Renew" : "Refresh",
+        (rc != 0) ? "failed" : "sent", (u32) rc);
+
+    vec_free(path_name);
+
+    return 0;
+}
+
+VLIB_CLI_COMMAND(test_ioam_profile_renew_refresh_cmd, static) =
+{
+.path = "test ioam profile-notification  ",
+.short_help =
+        "test ioam profile-notification path-name <string> start-index <index> num-profiles <number> <renew|refresh>",
+.function = test_profile_renew_refresh_fn,
+};
+
+static clib_error_t *set_scv_init_fn(vlib_main_t * vm,
+    unformat_input_t * input, vlib_cli_command_t * cmd)
+{
+    u8 *path_name = 0;
+    u32 start_index = 0, num_profiles = 0;
+
+    while (unformat_check_input(input) != UNFORMAT_END_OF_INPUT)
+    {
+        if (unformat(input, "path-name %s start-index %d num-profiles %d",
+                &path_name, &start_index, &num_profiles))
+            scv_init(path_name, num_profiles, start_index);
+        else
+            return clib_error_return(0, "unknown input `%U'",
+                format_unformat_error, input);
+    }
+    vec_free(path_name);
+    return 0;
+}
+
+VLIB_CLI_COMMAND(set_ioam_sc_init_command, static) =
+{
+.path = "set scv-init ",
+.short_help =
+        "set scv-init path-name <string> start-index <index> num-profiles <number>",
+.function = set_scv_init_fn,
+};
diff --git a/vnet/vnet/lib-scv/scv_util.h b/vnet/vnet/lib-scv/scv_util.h
new file mode 100644
index 00000000..fc0c73f4
--- /dev/null
+++ b/vnet/vnet/lib-scv/scv_util.h
@@ -0,0 +1,278 @@
+/* 
+ * scv_util.h -- Service chain validation/Proof Of Transit Utility Header
+ *
+ * Copyright (c) 2015 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef include_vnet_scv_util_h
+#define include_vnet_scv_util_h
+
+#include <vnet/ip/ip6_hop_by_hop.h>
+#define MAXDEGREE 1024
+#define MAXTOKENLEN 128
+#define debug_ioam debug_ioam_fn
+#define MAX_SERVICE_NODES 10
+/* Dont change this size 256. This is there across multiple components */
+#define PATH_NAME_SIZE  256
+
+/* Ring size. this should be same as the one in ODL. Do not change this
+   without change in ODL. */
+#define MAX_SERVICE_PROFILES 16
+
+/**
+ * Usage:
+ * 
+ * On any [service] node that participates in Service / Path verfication:
+ *
+ * Step 1: Initialize this library by calling scv_init()
+ * Step 2: Setup a Service chain validation profile that contains all the parameters needed to compute cumulative:
+ *         Call these functions:
+ *         scv_profile_find
+ *         scv_profile_create
+ *         scv_profile_set_bit_mask - To setup how large we want the numbers used in the computation and random number <= 64 bits
+ * Step 2a: For validator do this:
+ *          scv_set_validator
+ * Step 3a: At the initial Service node to generate Random number that will be read by all other nodes:
+ *          scv_generate_random
+ * Step 3b: At all service nodes including initial and verifier call this to compute cumulative:
+ *          scv_update_cumulative
+ * Step 4: At the verifier:
+ *         scv_validate
+ * 
+ */
+
+typedef struct scv_profile_
+{
+    u16 id;
+    u64 random;
+    u8 validator;
+    u64 secret_key;
+    u64 secret_share;
+    u64 prime;
+    u64 lpc;
+    u64 poly_pre_eval;
+    u64 bit_mask;
+    u64 limit;
+    u64 validity;
+    double primeinv;
+    // struct hlist_node my_hash_list; when this gets added to hashtbale
+} scv_profile;
+
+extern scv_profile *pow_profile;
+extern u16 pow_profile_index;
+extern u64 total_pkts_using_this_profile;
+extern u8 chain_path_name[PATH_NAME_SIZE];
+extern u16 invalid_profile_start_index;
+extern u8 number_of_invalid_profiles;
+extern f64 next_time_to_send;
+extern u32 time_exponent;
+
+/* 
+ * Initialize Service chain
+ */
+void scv_init(u8 * path_name, u8 max, u8 indx);
+
+/* 
+ * Get maximum number of profiles configured for this chain.
+ */
+u8 scv_get_max_profiles(void);
+
+/* 
+ * Find a SC profile by ID
+ */
+scv_profile *scv_profile_find(u16 id);
+
+static inline u16 scv_profile_get_id(scv_profile * profile)
+{
+    if (profile)
+    {
+        return (profile->id);
+    }
+    return (0);
+}
+
+/* setup and clean up profile */
+void scv_profile_create(scv_profile * profile, u64 prime,
+    u64 poly2, u64 lpc, u64 secret_share, u64 validity);
+/* 
+ * Setup profile as a validator
+ */
+void scv_set_validator(scv_profile * profile, u64 key);
+void scv_profile_cleanup(scv_profile * profile);
+
+/* 
+ * Setup max bits to be used for random number generation
+ */
+#define MAX_BITS 64
+void scv_profile_set_bit_mask(scv_profile * profile, u16 bits);
+
+/* 
+ * Given a random and cumulative compute the new cumulative for a given profile
+ */
+u64 scv_update_cumulative(scv_profile * profile, u64 cumulative, u64 random);
+
+/* 
+ * return True if the cumulative matches secret from a profile
+ */
+u8 scv_validate(scv_profile * profile, u64 cumulative, u64 random);
+
+/* 
+ * Utility function to get random number per pack
+ */
+u64 scv_generate_random(scv_profile * profile);
+
+int scv_profile_to_str(scv_profile * profile, char *buf, int n);
+
+extern void clear_ioam_scv_profiles();
+
+static inline u8 scv_get_profile_in_use(void)
+{
+    return pow_profile_index;
+}
+
+static inline
+    void scv_notification_reset(u16 start_index_recvd, u8 num_profiles_recvd)
+{
+    /* Profiles recevied w/o notn. Nothing to do. */
+    if (number_of_invalid_profiles == 0)
+        return;
+
+    /* Most likely case. Got all requested profiles */
+    if (PREDICT_TRUE(num_profiles_recvd == number_of_invalid_profiles &&
+            start_index_recvd == invalid_profile_start_index))
+    {
+        number_of_invalid_profiles = 0;
+        invalid_profile_start_index = 0;
+        return;
+    }
+
+    /* Received partial list */
+    if (num_profiles_recvd < number_of_invalid_profiles)
+    {
+        ASSERT(start_index_recvd == invalid_profile_start_index);
+        invalid_profile_start_index = (start_index_recvd + num_profiles_recvd)
+            % scv_get_max_profiles();
+        number_of_invalid_profiles -= num_profiles_recvd;
+    }
+
+    return;
+}
+
+int __attribute__ ((weak)) scv_profile_renew(u8 * path_name,
+    u8 start_index, u8 num_profiles);
+int __attribute__ ((weak)) scv_profile_refresh(u8 * path_name,
+    u8 start_index, u8 num_profiles);
+
+static inline u8 scv_is_decap(scv_profile * p)
+{
+    return (p->validator == 1);
+}
+
+static inline u16 scv_get_next_profile_id(vlib_main_t * vm, u16 id)
+{
+    int next_id, num_profiles = 0;
+    scv_profile *p;
+    u8 max;
+
+    max = scv_get_max_profiles();
+
+    next_id = id;
+
+    /* Check for new profile in the ring buffer until a valid one. Exclude
+       checking for the one already in use. */
+    for (num_profiles = 0; num_profiles < max - 1; num_profiles++)
+    {
+        next_id = (next_id + 1) % max;
+        p = scv_profile_find(next_id);
+        if (p->validity != 0)
+        {
+            vlib_cli_output(vm, "Current id: %d, New id: %d\n", id, next_id);
+            return (next_id);
+        }
+    }
+
+    return (id);
+}
+
+static inline void
+scv_profile_invalidate(vlib_main_t * vm, ip6_hop_by_hop_main_t * hm,
+    u16 id, u8 is_encap)
+{
+    scv_profile *p = scv_profile_find(id);
+    int rc;
+    u8 max;
+    f64 now = 0;
+
+    p->validity = 0;
+
+    /* If there are alredy profiles waiting. If so, use existing start_index. 
+     */
+    if (!number_of_invalid_profiles)
+        invalid_profile_start_index = id;
+
+    max = scv_get_max_profiles();
+
+    /* Check whether the id is already included in existing list */
+    if (!(id >= invalid_profile_start_index &&
+            id <= (invalid_profile_start_index +
+                number_of_invalid_profiles - 1) % max))
+    {
+        number_of_invalid_profiles++;
+    }
+
+    if (number_of_invalid_profiles > scv_get_max_profiles())
+        number_of_invalid_profiles = scv_get_max_profiles();
+
+    now = (f64) (((f64) hm->unix_time_0) +
+        (vlib_time_now(hm->vlib_main) - hm->vlib_time_0));
+    if (now <= next_time_to_send)
+        return;
+
+    if (is_encap)
+    {
+        rc = scv_profile_renew(chain_path_name,
+            (u8) invalid_profile_start_index, number_of_invalid_profiles);
+        if (rc != 0)
+            vlib_cli_output(vm,
+                "Renew notification- id start:%d,  num %d failed. rc: %d\n",
+                invalid_profile_start_index, number_of_invalid_profiles, rc);
+        else
+            vlib_cli_output(vm,
+                "Renew notification- id start:%d num %d sent. \n",
+                invalid_profile_start_index, number_of_invalid_profiles);
+
+    }
+    else
+    {
+        /* Non encap node. Send refresh notification for now. Later set a
+           timer and if there is no profile even after the timeout send
+           refresh notification. */
+        rc = scv_profile_refresh(chain_path_name,
+            (u8) invalid_profile_start_index, number_of_invalid_profiles);
+        if (rc != 0)
+            vlib_cli_output(vm,
+                "Refresh notification- id start:%d,  num %d failed. rc: %d\n",
+                invalid_profile_start_index, number_of_invalid_profiles, rc);
+        else
+            vlib_cli_output(vm,
+                "Refresh notification- id start:%d num %d sent. \n",
+                invalid_profile_start_index, number_of_invalid_profiles);
+    }
+    next_time_to_send = now + time_exponent;
+    time_exponent <<= 1;        /* backoff time is power of 2 seconds */
+
+    return;
+}
+
+#endif